It is believed that it was his activities during the First Wizarding War and his time as an Auror that led to Moody losing a leg (replaced by a wooden prosthesis). His work also led to significant facial scarring, including losing a piece of his nose in his fight with Rosier.
Moody's corpse was recovered by the Death Eaters, and his magical eye was taken by Dolores Umbridge, who used it to keep track of her subordinates in the Ministry of Magic. When Harry Potter, Hermione Granger, and Ron Weasley broke into the Ministry, Harry found the eye and was revolted by how it was being used.
It was during his time as an Auror that he fought against the evil forces of Voldemort and his loyal Death Eaters as they began to rise as a diabolical power in what has since been referred to as the (First) Wizarding War. This very war would claim Moody's eye and leg, as well as leave several scars upon his face.
How can Mad-Eye Moody see through the invisibility cloak?
A fake eye belonging to Alastor 'Mad-Eye' Moody, the enchanted device had an electric blue iris and could rotate 360 degrees in the wearer's head. The eye was able to see through anything, including the back of Moody's own head and even invisibility cloaks, and was the reason that Moody became known as 'Mad-Eye.
How did Umbridge get Mad-Eye Moody’s Eye ? (Harry Potter Explained)
Did Snape know Harry was under the Invisibility Cloak?
Dumbledore was doing James a favour by helping him pass down the Invisibility Cloak to his son Harry. Snape definitely knew because in book 4 when Harry sees crouch in Snapes office, he's in his invisibility cloak. As soon as snape sees the golden egg and the map he says 'potters here' to mad eye. Potters here.
In July 1997, Moody was killed by Lord Voldemort during the Battle of the Seven Potters. Moody's corpse was recovered by the Death Eaters, and his magical eye was somehow taken by Dolores Umbridge, who used it to keep track of her subordinates in the British Ministry of Magic.
Barty Crouch Jr. drank Polyjuice Potion out of Moody's hipflask regularly, in imitation of the real Moody, and expressed many of Moody's normal eccentric habits. Doing this allowed him to impersonate Moody for almost the whole year without raising suspicion. All the while, Crouch did his part in Voldemort's plan.
He kept Moody alive under the Imperius Curse to continue harvesting hair for the Polyjuice Potion, and to question him about his personality, behaviour and knowledge, in order to make the act more convincing.
The "seven Potters" and their protectors were: Harry with Rubeus Hagrid, on the flying motorbike of Sirius Black; Hermione Granger with Kingsley Shacklebolt, on a Thestral; Ron Weasley with Nymphadora Tonks, on a broomstick; George Weasley with Remus Lupin, on a broomstick; Fred Weasley with Arthur Weasley, on a ...
Harry describes Umbridge to Sirius Black, saying that she's vile enough to be a Death Eater, despite not being one. Umbridge is also depicted to be a prejudiced person, despising half-breeds and Muggle-born witches and wizards to the point of firing Hagrid due to his half-giant birth status.
His fears were assuaged in 1944, when he received a Hogwarts letter and began attending the school, where he was sorted into Hufflepuff, but he never forgot about his sister. He attended Hogwarts around the same time as future mediwitch Poppy Pomfrey.
Throughout the series, he is an anti-hero due to overly-cautious and paranoid side when it comes about his personal security, but anyone who dies fighting Lord Voldemort himself isn't a villain, that aside even though Moody may look crazy as all heck but he's not a bad guy.
Mad-Eye Moody had earned the trust and respect from the likes of Albus Dumbledore, so no one would have ever suspected it was all one big ruse to lead Harry into the hands of Lord Voldemort. You know it's a good trick when even Dumbledore is convinced by your disguise and doesn't suspect a thing from you!
On turning eleven, Umbridge started attending Hogwarts School of Witchcraft and Wizardry. She was Sorted into Slytherin and her head of house was Horace Slughorn.
The reader finds out Dumbledore knew beforehand because he calls in the house elf Winky before Crouch changes back from Moody form. How did Dumbledore know beforehand? He guessed. It involved Harry telling Dumbledore that Barty Crouch Sr.
During the 1994–1995 school year, Barty Crouch Jnr (disguised as Alastor Moody) transformed student Draco Malfoy into a white ferret and bounced him up and down, as punishment for attempting to attack fellow student Harry Potter from behind, earning Draco the nickname of "The Amazing Bouncing Ferret".
In the film version, Barty Crouch Jr. has the habit of licking his lips when threatened, in a snake-like way, to which he occasionally shows while under the disguise of Alastor Moody. This action led to him giving himself away to his father following the second task of the Triwizard Tournament.
Lucius Malfoy was one of the many Death Eaters who denied their allegiance to Voldemort after the end of the First Wizarding War and therefore would be a perfect example of the kind of person Barty Crouch Jr. hates the most.
In Harry Potter and the Deathly Hallows, Fred and George are members of the Order of the Phoenix and serve as two of Harry's six decoys when he escapes Privet Drive. George loses one of his ears to Snape's Sectumsempra curse (which was aimed at a Death Eater's wand hand, but missed).
After Voldemort's defeat by Harry at the Battle of Hogwarts and the restoration of the Ministry of Magic by the new Minister, Kingsley Shacklebolt, Umbridge was sentenced to life imprisonment in Azkaban for her crimes against Muggle-borns.
Moody was killed shortly after they took off so they knew his body wasn't that far from the Dursleys. The Death Eaters found it and took his eye, giving it to Umbridge as a gift for her services. As for the rest of his body, remember that he had fallen a few hundred or thousand feet from the air so it would be a mess.
